Cleaner with double wash water box



April 11, 1944.

` c. E. FRASER CLEANER WITH DOBLE WASH WATER BOX Filed June 25, 1940 ATTORNEY.

Patented Apr. 11, 1944 UNITED STATES PATENT OFFICE l a .2,346,215 i CLEANER WITH DOUBLE' WASH WATER BOX Charles E. Fraser, Kew (3ra1'dens,-N. Y.

Application June 25, 1940, Serial 342,249

6 Claims. (Cl. 210-128) The present invention relates to a method of and mechanism for cleaning filter beds.

It is common practice in the treatment of sewage, industrial wastes, etc., to pass liquids containing the same through relatively shallow beds of sand, aggregate or the like, which removes the solids therefrom. Such beds, in the course of time, become Vclogged with the retained material, even-,though the raw material undergoing treatment hasgbeen subjected to preliminary treatment such as sedimentation or the like. As a consequence, it ,becomes necessary to restore the bed to somewhere near its initial solid removal capacity and vthis may be done by cleaning it either intermittently or continuously.

A popular typejof vcleaning mechanism for the above purpose consists of a-travelling cleaner operatedabove the bed, .which includes a cleaner caisson. The caisson is intended to make a sealing contact, with the portion of the bed immediately thereunder and thisis accomplished usually by extending thesidewalls of the caisson into the bed material a suiicient distance and by providing sealing means, such as hollow, rotating drums at each endvof the caisson and sliding contact along the sides. Consequently, the small portion of the bed whichis being cleaned is temporarilycompletely cutoff from a ltering action.

The cleaner caisson may be divided into two compartments, in the rst of which the lter bed material is agitatedand theretained solids loosened therefrom, the .wash water resulting.. from such action passing overinto,` the second or wash Water compartment from which it is removed by a pump for disposal or 'further treatment.

In downil'ow filters, it is customary to iiow the unltered inilu'ent, with or without previous treatment, such as sedimentation, directly on top of the filter bed, the vliquidpassing through the bed, thersolids being caught thereby and clean eflluent resulting. lThis eluent then moves from beneath the bed and into a disposal channel, the level of which is maintained slightly below the level of iniluent so as tol provide a suiiicient hy-l thehydraulic head between the influent and eillu-l ent levels. This usually consists in arranging the parts so that the influent will automatically build up to a higher level than that of the eluent. This may conveniently take the form of an adjustable weir on the eiiluent discharge. This weir may be;

automatically operated within a narrow range, by a float on the inuent side of the lter.

A convenient method of agitating a portion of the lter bed to clean-the same may take the form of an intermittently operated solenoid Wherev thebed material is of the magnetite sand variety. This electromagnet, submerged in the liquid,.being locatedrelatively close to the bed, when energized-for the space of abouta second, .lifts a section of themagnetite sand immediately thereunder and this movement andthe subsequent dropping of the sand back into the bed, tendsto separate the solids caught by the sand therefrom. Inasmuch as the liftingof this magnetite creates a zone of lessened resistance in the bed at that point, if, as in a downlow lter,the eluentlevel is higher than the Wash water level in the solenoid compartment in the caisson,there will be a back rush of clean eluent up through the bed at the area of lessened resistance, which Washes the loosened solids from the magnetite, over the partition between the agitation compartment-and wash water box and into the latter from which it is removed by a pump. This cleaning procedure may take place continuously. 4, Y

Other'mechanismfor creating the area of agitation in the bed other than an electromagnetmay consist of pipes projecting a suitable distance into. the. bed material either to simply disturb the vbed or this disturbance may be'facilitated by injecting air or other liquid through .the pipes. These methods of agitation are also suitable for a bed of sand Orother aggregatenot ofthe magnetite variety.

Inupflow lters, much the same procedure takes place although in'ltliat case, the influent to be filtered iiows from beneath the-bed, up through the bed materiahthejclean eiiiuent being on top thereof. As before, the influent level must/be above that of the effluent in order to induce ^this vhydraulic flow. Likewise, the cleaner mechanism l Inboth cases,l it is to be noted that the'cleaner caisson deiines an area ofresi'stance against the l flow of liquid therethrough andis cut od from the liquid surrounding it by the seals whichexistr at the side and ends thereof and that consequently, no filtering action takes place in thearea covered by the cleaning mechanism. ,l

The main function of, theuseals'is to assist the Wash water pump to create a back head Iand prevent the wash water from contaminating the eiiluent. In the case of downflow ltersv, the seals also prevent the unltered influent from above the bed leaking into thev cleaner caisson and from thence through the bed at 'its area of lessened resistance to thus contaminate the clean eluent below. In the case of upilow filters, the seal prevents therush of unfiltered iniiuent moving up through the area of lessened resistance in thebed from leaking outwardly through the cleaner caisson to contaminate the clean eilluent above the bed.

During the cleaning operation where there is an upflow of liquid through the zone of agitation, the washwater carrying the dirt flows into a compartment from which it is removed. In order to reach the wash water compartment for removal,

the dirty water usually flows over the top of an intermediate wall which may or may not bev topped with an adjustable weir. there is a tendency to carry with it some of the sand or bed aggregate which is subsequently lost. This is due to the fact that such intermediate wall is usually of restricted extent and consequently a large amount of liquid at high velocity must pass -thereover duringsuch operation.

`IIt is the principal object of the present invention toprevent this loss of bed material by providing an extended Wall and/or we ir which as a consequence proportionately decreases the velocity of ow thereover. As a matter Of fat, in such case the volume of liquid overflowing the wall In so doing,

moving through the space 6, up a vertical channel and over an adjustable weir 22. This Weir determines the eiiluent level E at an elevation sufciently lower than the influent level I so as to create a hydraulic head tending to move liquid through the bed in a downward direction.

During a cleaning operation, the Weirs I6 which separate the agitation compartment II from the Wash water compartments I8 are adjusted so as Vto establish a wash water level W sufliciently `lower than eiiluent level E so that when an area of agitationl is ,created in the bed below the channel I'I, with a consequent area of lessened resistance there, clean eiiiuent will rise through the bed at into the wash water compartment may even be increased over that normally existing and still obtain the desirable results obtaining from a decreased velocity of ilow.

The invention further contemplates the provision of a plurality of wash Water boxes on two sides of the agitation producing means. As a consequence, the upilow of Wash water has an outlet in two directions, all of which makes for more efficient washing and total operations.

The invention vfurther consists in the novel arrangement, combination and construction of parts more fully hereinafter described and shown in the accompanying drawing, in which- Fig,` l is a side elevation partly in section of an apparatus embodying the present invention;

Fig. 2 is a sectional plan View ofthe combination. of Fig. ,1.

Referring now to Fig. l, the usual filter bed is shown at I of sand, such as that of the magnetite or .silica variety er any `other aggregate or filter media. A suitable thickness of bed material rests upon a screen 2 supported by grid 3 resting upon the'top of wall' 4 so as to slightly space the grid from thebottom 5 of the filter tank leaving a space 6 therebetween.

A suitable cleaning mechanism may consist of a trolley 'I movable through wheels 8 driven by any y suitable source of power, on trackway 9. Depending from the trolleyis a caisson consisting of front wall I0, rear wall I I and side walls I2. A solenoid or other agitation creating means is located between front and rear walls I0 and I I and adjacent intermediate walls I 4 and I5, each of Which is topped by an adjustable weir I6. As shown, the solenoid I3 is in what maybe termed an agitation compartment I'I, while on each side thereof are wash water compartments I8. Each of the latter is provided with a pump I9 for removing dirty water therefrom.

At the front and rear of the cleaner and mounted between side Walls I2 thereof are rotatable sealing drums having rubber wiper seals 2| at the ends thereof making a water tight connectionrwith the side walls I2. The latter extend a; suiiicient distance into the bed material so that with the drums 2li an area is eiTectively sealed against a filtering operation during the bed cleaning period.

In a downflow filtering system, iniluent to a desired level I is ilowed on top of the bed, the liquid passing through the bed, the clean eiiluent that point, wash the retained solids therefrom, pass over the welrs IB and into the Wash water compartments, from which the dirty Water is removed.

As shown, a solenoid may be used as the agitation creating means by suitable connection to an intermittent source of electrical energy so as to energize the same. Upon establishing this connection, Where the sand of the lter bed is of the magnetite variety, the latter is magnetized and an area thereof bodily lifted up toward the solenoid which' loosens the dirt adherent to and caught by the sand. During this time, clean eliiuent carries the loosened dirt into the wash Water compartments. When the solenoid is deenergized, it releases the magnetite, which drops back into the bed substantially clean. This cleaning operation is then repeated Vintermittently until the entire area, of the bed has been subjected to the purging action.

In cleaning devices of the present type heretofore used, there has been but a single wash water box and single weir over which wash water flows. In the present instance, it is to be noted that the lineal extent of weir has been doubled. As a consequence, the velocity of the same volume of Water may be materially decreased. This has the decided advantage that the bed material has an opportunity to settle rather than to be carried over into the Wash water compartments, removed and thereby lost.

On the other hand, Where the'bed material is composed of particles of sumcient size such that there is no great danger of them passing over the weir, the volume of Water rising in the channel I1 to remove the dirt may be doubled. The fact that there are independently adjustable weirs makes it possible to now the wash water preferentially either to one side or the other of the solenoid at will. v

As a consequence of this combination, bed material of smaller particle size and therefore lighter weight may be used where the velocity is cut down, all of which makes for a cheaper rst cost in bed installation as well as cheaper replacement costs.

On the other hand, Where larger and heavier aggregates are used as the bed material, the upflow velocity of water for the removal of solids may be correspondingly increased.

While the invention has been shown and described with particular reference to specific embodiments, it is to be understood, that it is not to be limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

I claim:

l. In combination, a travelling cleaner for a lter bed including means to seal off a section of a caisson including a plurality of Wash water compartments having closed bottoms and an intermediate bed washing channel open at its bottom, each wash water compartment communicating with the bed washing channel at a predetermined liquid level lower than the liquid level effective upon the underside of the bed to cause liquid to move up through the bed into the washing channel, then flow into each of the wash water compartments wen the liquid level in the wash water compartments is below said predetermined liquid level, means to agitate the filter' bed in said sealed off portion to facilitate the upward flow of water therethrough and means to remove the wash water from the wash water compartments.

2. In combination, a travelling cleaner for a filter bed including means to seal oi a section of the bed from a filtering action, the cleaner having a caisson with front, rear and side walls and two intermediate walls extending laterally of the caisson, thus forming two end wash water compartments each communicating with an intermediate bed washing channel, means to create a zone of agitation in the bed beneath the channel, each of the channel walls having an adjustable weir, means to now liquid up through the channel over the weirs and into the wash Water compartments, and means to remove wash water therefrom.

3. In combination, a cleaner for a filter bed including a caisson having side walls making sealing contact with the bed, means at each end o f the cleaner and between the side walls thereof for making a sealing contact with the bed, the caisson having two separated wash water compartments with closed bottoms, means to remove wash water therefrom, and an intermediate channel with an open bottom, with means therein for creating a zone of agitation in the bed beneath the channel the wash water compartments communicating with the intermediate channel.

4. The combination of claim 3 in which the front and rear walls of the channel carry adjustable weirs, whereby the height of the wall above the bed may be regulated.

5. A lter bed cleaner including a caisson having front, rear and side walls, means to make sealing contact with a filter bed so that an area thereof is sealed 01T from a ltering action, the caisson having two separated wash water cornpartments with closed bottoms, means to remove wash water therefrom, and an open bottom intermediate channel between the wash water compartments and communicating therewith, and means in the channel for creating a zone of agitation in the bed therebeneath.

6. In combination, a travelling cleaner for a filter bed, including means to seal oi a section of the bed from a ltering action, the cleaner having a, caisson, including a plurality of wash water compartments with closed bottoms and an intermediate bed washing channel open at its bottom, each wash water compartment communicating with the bed washing channel at a predetermined liquid level, means for creating a zone of agitation in the bed beneath the channel, and means to remove the wash water from each of said compartments, said predetermined liquid level being lower than the backhead liquid level eiective upon the underside of the bed.

CHARLES E. FRASER. 

